Railway trucks with pivotally connected side frames

ABSTRACT

Railway trucks for rapid circuit transit service are, in the interest of weight reduction without corresponding reduction in strength or riding qualities, formed with a pair of side frames supported at their ends from both axles and resiliently pivoted to each other on a generally transverse axis. To provide limited resilient support for propulsion and brake equipment supported by the side frames, without permitting excessive vertical movement of third rail collection equipment mounted on the side frames, the support of the side frames on the axle boxes is effected by slightly resilient single layer elastomeric chevron spring devices, the slight resilience of the chevron spring devices being sufficient to minimize necessary pivoting of the side frames about their transverse axis.

[ June 18, 1974 1 RAILWAY TRUCKS WITH PIVOTALLY CONNECTED SIDE FRAMES [75] Inventor: Richard L. Lich, Town and Country, Mo.

[73] Assignee: General Steel Industries, Inc., St.

Louis, Mo.

22 Filed: Sept. 12,1972

211 Appl. No.2 288,267

[52] US. Cl...... 105/199 R, 105/182 R, 105/206 R, 105/2081, IDS/224.1

FOREIGN PATENTS OR APPLICATIONS 1,043,217 9/1966 Great Britain 105/2082 Primary Examiner-Lloyd L. King Assistant Examiner-Howard Beltran Attorney, Agent, or Firm-F. Travers Burgess [5 7] ABSTRACT Railway trucks for rapid circuit transit service are, in the interest of weight reduction without corresponding reduction in strength or riding qualities, formed with a pair of side frames supported at their ends from both axles and resiliently pivoted to each other on a generally transverse axis. To provide limited resilient support for propulsion and brake equipment supported by the side frames, without permitting excessive vertical movement of third rail collection equipment mounted on the side frames, the support of the side frames on the axle boxes is effected by slightly resilient single layer elastomeric chevron spring devices, the slight resilience of the chevron spring devices being sufficient to minimize necessary pivoting of the side frames about their transverse axis.

15 Claims, 12 Drawing Figures RAILWAY TRUCKS WITH PIVOTALLY CONNECTED SIDE FRAMES BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to railway rolling stock and consists particularly in a four-wheel truck with relatively pivoted side frames.

2. The Prior Art Prior patents, e.g., Haynes, U.S. Pat. No. 2,477,517, disclose four-wheel trucks in which separate side frames are pivoted to each other on a transverse axis to accommodate differing vertical conditions in the opposite track rails. Commonly, the side frames of such trucks are rigidly mounted on the journal boxes or are tightly clamped to the journal boxes such that substantially no vertical movement is permitted between the side frames and the respective journal boxes. This arrangement necessitates substantial pivoting of the side frames relative to each other and provides disadvantageous nonresilient support for motors and drive equipment, as well as brake gear, from the side frames, which would increase wear and the likelihood of damage to these parts by reason of their subjection to full vertical forces received by the wheels from the rails.

SUMMARY OF THE INVENTION The invention provides a four-wheel railway car truck in which the support of the truck side frames on the axles is sufficiently resilient to prevent transmission of damaging vertical shocks to motors, drive equipment and brake gear supported on the side frames, yet sufficiently stiff to prevent excessive vertical movement of third rail collection equipment supported on the side frames. Adequate equalization is provided, despite the limited resilience of the support of the side frames on the journal boxes, by pivoting the side frames to each other on a generally transverse axis.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view of a truck embodying the inventron.

FIG. 2 is a side view of the truck illustrated in FIG. 1.

FIG. 3 is a transverse vertical sectional view along line 3-3 of FIG. 1.

FIG. 4 is a fragmentary transverse vertical sectional view along line 4-4 of FIG. 1.

FIG. 5 is a fragmentary horizontal sectional view along line 5--5 of FIG. 2.

FIG. 6 is a transverse vertical sectional view, similar to FIG. 3, of a second form of the invention.

FIG. 7 is an enlarged fragmentary transverse vertical sectional view of one of the connections between the side frames of the truck illustrated in FIG. 6.

FIG. 8 is a fragmentary longitudinal vertical sectional view along lines 88 of FIGS. 6 and 7.

FIG. 9 is a transverse vertical sectional view, similar to FIGS. 3 and 6, of a third form of the invention.

FIG. 10 is an enlarged fragmentary transverse vertical sectional view of one of the connections between the side frames of the truck illustrated in FIG. 9.

FIGS. 11 and 12 are longitudinal vertical sectional views along lines 11-11 and I2l2 respectively of FIG. 10.

DETAILED DESCRIPTION The numeral 1 denotes railway flanged wheels arranged in gauged pairs on driving axles 3 which are parallel to each other and spaced apart from each other with corresponding wheels lying in the same vertical planes perpendicular to the axles.

Inwardly of wheels 1, axles 3 are rotatably received within bearings 5. Bearings 5 are provided with an adaptor 7 having upwardly and inwardly symmetrically inclined sides 9, Adaptor sides 9 are V-shaped in plan with their apices pointing away from the respective axles in a direction longitudinal of the truck.

A pair of side frames comprising respectively longitudinally extending side members 11L and 11R and transverse transom members 13L and 13R are supported on the respective bearings 5 by means of elastomeric chevron springs each comprising a V-shaped elastomeric pad 15 bounded by a pair of V-shaped metal plates 17 and 19, the inner plate 17 of each chevron spring being secured to the surface 9 of the bearing adaptors 7. Each of the side frames is formed at its ends with downwardly open pedestal jaws having inwardly and upwardly inclined sides 21 of the same but concave V shape in plan as the chevron springs and the outer metal plates 19 of the latter are received in and secured to pedestal sides 21.

The elastomeric material in pads 15 of the chevron springs is of sufficient stiffness that through its resistance to compression it virtually eliminates any relative longitudinal movement of the side frames relative to the journal boxes and holds the journal boxes against substantial lateral movement relative to the side frames, while permitting a limited amount of vertical movement of the side frames on the journal boxes, sufficient to cushion equipment supported from the side frames against receipt of the full force of vertical impacts received by the wheels from the rails, yet insufficient to require excessive movement of third rail shoes supported by the side frames. Included among the equipment supported by the side frames as noted above may be traction motors M and associated gear boxes G.

In view of the limitations imposed upon the chevrons by the necessity of preventing excessive movement of third rail shoes S, it is necessary that the side frames be connected to each other so as to pivot about a transverse axis sufficiently to accommodate the wheel treads to differing vertical irregularities in the opposite track rails in excess of the normal deflections of the chevron pads. For this purpose transom members 13L and 13R are slightly offset from each other longitudinally of the truck and extend parallel to each other in a direction transverse of the truck to a region close to the opposite side frame, and above their respective extremities 231. and 23R the opposite side frames are widened respectively to form downwardly facing inwardly extending stub members 25L, 25R.

Details of the construction of the connections of the side frames to each other are shown in FIG. 4, in which it will be seen that the upper surface of extremity 23L of transom member 13L is formed with an upwardly open circular recess defined by a cylindrical rim 27L and having an upwardly facing bottom wall 29L. While the .bottom surface of stub member 25R is formed with a similar downwardly open cup-shaped recess defined by a downwardly extending cylindrical rim 31R and having a downwardly facing bottom wall 33R. Walls 29L and 33R are circularly centrally apertured at 35L and 37R respectively and a large elastomeric annulus 41 is seated in the space between walls 29L and 33R surrounded by rims 27L and 31R and is held compressed therein by an assembly comprising a tension member in the form of a bolt 39, a metal washer 41 and an elastomeric washer 43 above wall 33R and a similar elastomeric washer 43 and metal washer 41 surrounding the bolt below wall 29L, and a nut 45 on the lower end of bolt 39 holding washers 43 and elastomeric annulus 41 in compressed condition and tying right-hand side frame stub member 25R to left-hand transom member extremity 23R. Yieldability of elastomeric annular pads 41 permits limited pivoting of the side frames relative to each other about a generally transverse axis to provide equalization for the truck. To assure adequate flexibility in the connections between side frame stub members 25R or 25L and transom members 13L or 13R, bolts 39 are of somewhat less diameter than apertures 35L and 37R and elastomeric washers 43 are formed with annular ribs 47 surrounding their central openings and insertible in apertures 35L and 37R to maintain the bolts in spaced relation to the sides of the apertures.

In the center of the truck each of the transom members 13L and 13R is formed on opposing transverse surfaces with a semicircular recess 49 to form a vertical axis pivot bearing for a cylindrical boss 51 depending from a transverse bolster 53 supported at its sides by sliding bearings 55 on the midsections 57L and 57R of side frame side members 11L and 11R. A generally similar pivot arrangement is shown in FIGS. 1 and 3 of my US. Pat. No. 3,523,505. Bolster 53 mounts at its ends largely outwardly of side frame side members 11L and 11R upright springs 59 adapted for supporting securement to the underside of a car body (not shown), and at its ends bolster 55 has brackets 61 to which are secured longitudinally extending bolster anchors 63, the opposite ends of which are similarly secured to brackets 65 depending from the supported car body whereby to hold bolster 55 against swiveling relative to the car body and transmitting acceleration and retardation forces from the bolster to the car body, while permitting vertical and lateral movements of the car body on springs 59.

To assure the smoothly functioning conjugate relationship between the side frame transom member extremities 23L and 23R and the corresponding side frame stubmembers 25R and 25L, the two side frames are preferably formed as a single one-piece casting and with rims 31R and 27L, and 31L and 27R, respectively, integral with each other, the pockets between them being formed by precision cores. Upon completion of the castings, the side frames are separated from each other by burning the circular walls 27L, 31R and 27R, 31L apart intermediate their ends to form the respective opposing rims 27L and 31R or 27R and 31L. By this mode of manufacture, proper fitting without extensive machining of opposite pairs of side frames with each other will be assured.

Operation of the truck is as follows: Vertical impacts are cushioned by the limited resiliency of chevron pads 15, thus reducing wear and the likelihood of damage to equipment mounted on the side frames, but the limited resiliency of the pads does not cause sufficient vertical movement of the side frames to interfere with normal operation of third rail shoes by requiring excessive movement of the shoes to maintain their contact with the third rail. At the same time, additional relative movement between the side frames necessary to accommodate to differing vertical irregularities in the two track rails is permitted by the action of annular elastomeric pads 41 between transom member extremities 23L and 23R and side frame stub members 25R and 25L, only limited movement being required between the side frames because of the limited resiliency of chevron pads 15, the equalization thus being a combination of the effect of chevron pads 15 and the pivoting of the side frames permitted by annular pads 41. Pivoting of the side frames relative to each other is further facilitated by the use of slightly resilient side bearings 55 and the provision of an elastomeric bushing 50 in the annular space between bolster boss 51 and transom stub recesses 49.

In the modified constructions illustrated in FIGS. 6-8 and 9-12, identical parts bear the same reference characters as in the first embodiment, and modified or different parts are identified by different reference characters.

The truck of FIGS. 6-8 is similar to that of the first embodiment except in the form of the transom members 73L and 73R and side frame stub members 75L and 75R,

Both transom members 73L and 73R are identical. I

Transom member 73R shown in FIG. 7 is of box section, with spaced top and bottom walls 77R and 79R, and at its extremity adjacent side frame 11L, top wall 77R is formed with a recess 81L of generally concave, generally hemispherical shape and transeversely inboard of the truck from recess 81R, both top and bottom walls are formed with vertically aligned circular openings 83R and 85R.

Stub member 75L projects inwardly from side frame llL in transverse alignment with transom member 73R and in overlying relation with the adjacent extremity thereof. A depending hemispherical boss 87L, of slightly less diameter than recess 81R, is formed on bottom wall 89L of stub member 75L for registry with recess 81R in which it is received. To prevent metal-to metal contact and consequent wear between boss 87L and recess 81R and to facilitate pivotal movements therebetween, a hemispherical pad 91 of elastomeric material is interposed between the recess and boss. Stub member 75L projects inwardly transversely of the truck from boss 87L and the projecting portion of bottom wall 89L is fomied with a circular opening 93L, which is vertically aligned with openings 83R and 85R when boss 87L and recess 81R are in registry with each other. For holding stub member 75L and transom member 73R in engagement with each other through boss 87L, pad 91 and recess 81R, a pair of annular elastomeric pads 95 are seated respectively on the top of stub member bottom wall 89L and the transom member bottom wall 79R, with inner annular ribs 97 projecting into openings 93L and 85R respectively, and a bolt 99 passes through the holes in pads 95, metal washers 101 being interposed respectively between the bolt head 103 and upper pad 95 and between nut 105 on the lower end of bolt 99 and lower pad 95, the latter being tightened to compress pads 95 and thereby hold stub member 75L and transom member 73R in pivotal relation with each other about an axis transverse of the truck so as to permit necessary longitudinal tipping movement of side frames 11L and 11R with respect to each other.

The truck of FIGS. 9-12 is similar to those of FIGS. 1-5 and 6-8 except in the fonn of the transom mem bers 113R and 113L and the side frame stub members llSL and 115R.

Both transom members 113R and 113L are identical, as are side frame stub members llSL and 115R. Transom member 113R is of tubular shape and its end portion 117R adjacent the opposite side frame 11L is of reduced diameter, being joined to it by an annular wall portion 119R. Side frame stub member 115L is of the same tubular cross section as transom member 113R os that its interior surface l21L is of somewhat larger diameter than the end portion 117R of the transom member, and when the truck is assembled, transom member end portion 117R is matingly received within side frame stub member 115L, the end of stub member llSL being spaced transversely of the truck from transom member annular wall 119R. To prevent metal-to-metal contact between transom member end portion 117R and the side frame stub member interior surface l2lL and consequent wear and noise, and to facilitate pivotal movements between these elements, an elastomeric bushing element consisting of inner and outer arcuate metal plates 122 and 123 and elastomeric blocks or pads 125, is compressed between surface 12lL and the outer surface of transom stub end portion 117L, relative pivotal movement being accommodated by shear in pads 125.

In bushings 122, 123, 125, as best seen in FIG. 12, inner plates 122 are arcuately spaced from each other, as are outer plates 123, the angular positions of the inner and outer plates being staggered with respect to each other, so that the end portions of each outer plate overlaps the end portions of two adjacent inner plates, and each pad 125 is bonded to the overlapping portions of an inner and outer plate. This arrangement facilitates application of the bushing element and relative pivotal movement between transom member 113R and side frame stub member 115L.

For ease of manufacture and to insure proper mating between transom members 113R and ll3L and side frame stub members llSL and 115R, the entire truck frame may be formed as a one-piece casting, in which the transom members 113R, ll3L are joined to the side frame stub members ll5L, 115R by short arcuately spaced arcuate extensions 127 of their peripheral walls, the annular and transverse spaces between them being formed by precision ceramic cores in the mold in which the truck frame is cast. After the casting is completed, exteriors 127 are burnt off, or otherwise removed, to separate the side frames from each other.

The details of the structure may be varied substantially without departing from the spirit of the invention and the exclusive use of those modifications coming within the scope of the claims is contemplated.

I claim:

1. A railway vehicle truck comprising a pair of axles spaced apart longitudinally of the truck, wheels mounted on the end portions of said axles, transversely spaced longitudinally extending side frames adapted to support current collection equipment intermediate their ends, said side frames having downwardly open jaws at their ends embracing the end portions of said axles, bearing devices mounted'on said axles within said jaws, said jaws and said bearing devices having longitudinally spaced opposing respectively downwardly and upwardly facing transverse surfaces upwardly and inwardly inclined toward each other, said transverse surfaces being V-shaped in plan with their apices pointing longitudinally of the truck, a single pad of elastomeric material between each pair of opposing bearing device and jaw tranverse surfaces, said pads being sufficiently stiff to resist substantial vertical movement of said side frames and thereby prevent excessive variation in the height of current collection equipment carried thereby while being sufficiently resilient to provide adequate vertical cushioning for equipment supported from said side frames, and means connecting said side frames to each other for sufficient relative pivotal movement about a generally transverse axis to maintain, in cooperation with said pads, all said wheels in constant load-bearing engagement with the supporting track irrespective of varying vertical irregularities in the track rails.

2. A railway vehicle truck according to claim 1 wherein said side frame connecting means comprises a substantially straight transverse transom member on each side frame extending toward and terminating in close proximity to the opposite side frame, said transom members being located symmetrically on opposite sides of the transverse axis of the truck, an inboard stub member on each side frame in transverse alignment with the transom member of the opposite side frame, and flexible connections between the transom members and corresponding stub members.

3. A railway vehicle truck according to alcim 2 wherein said transom members have opposing surfaces transverse of the truck closely spaced apart longitudinally of the truck and formed with concentric arcuate recesses in their opposing transverse surfaces, there being a transverse bolster slidably supported on said side frames and having a central depending pivot boss pivotally received between said arcuate recesses, upright springs carried by the ends of said bolster for supporting a vehicle body thereon, and means for connecting said bolster to a supported vehicle body for preventing swivel movements therebe'tween while permitting vertical and transverse deflection of said springs.

4. A railway vehicle truck comprising a pair of axles spaced apart longitudinally of the truck, wheels mounted on the end portions of said axles, transversely spaced longitudinally extending side frames supported at their ends on the end portions of said axles, each said side frame being formed with a transverse transom member extending toward and terminating in close proximity to the opposite side frame, said transom members being located symmetrically on opposite sides of the transverse axis of the truck, an inboard stub member on each side frame in transverse alignment with the transom member of the opposite side frame, and flexible connections between the transom members and corresponding stub members.

5. A railway vehicle truck according to claim 4 wherein said side frame stub members overlie the end portions of the corresponding transom members.

6. A railway vehicle truck according to claim 5 wherein said pivotal connections comprise opposed respectively upwardly and downwardly facing horizontal surfaces on said transom members and said side frame stub members, a pad of elastomeric material interposed between said surfaces, and means tying said transom members and the corresponding stub members to each other vertically and thereby compressing said elastomeric pads.

7. A railway vehicle truck according to claim 6 wherein said tying means comprises a vertical tension member passing through said opposed surfaces and said elastomeric pad, additional elastomeric pads surrounding said tension member on upwardly and downwardly facing surfaces respectively of said stub members and said transom members, and means on said tension member compressing said additional pads against the respective last-named surfaces.

8. A railway vehicle truck according to claim 7 wherein depending and upstanding rims respectively encircle said downwardly and upwardly facing surfaces respectively of said stub members and said transom members, said elastomeric pads being of annular shape.

9. A railway vehicle truck according to claim wherein said pivotal connections comprise opposed downwardly and upwardly facing spherical surfaces on said stub members and transom members respectively, there being a pad of elastomeric material interposed between said surfaces, and means spaced transversely of the truck from the respective opposed spherical surfaces for tying the corresponding transom member and stub member to each other vertically and compressing said elastomeric pads.

10. A railway vehicle truck according to claim 9 wherein each of said stub members is formed with a projection extending transversely from said downwardly facing surface away from the related side frame, and said tying means comprises a vertical tension member passing through said projection and the corresponding transom member.

11. A railway vehicle truck according to claim 10 wherein additional elastomeric pad devices are seated on upper and lower surfaces of said projection and the corresponding transom stub surrounding said tension member, there being means on said tension member for compressing said additional pads against said lastnamed surfaces.

12. A railway vehicle truck according to claim 4 wherein said transom members and said stub members are of tubular crosssection, one of said members having an end portion of reduced cross-section to permit mating insertion of the former into the latter.

13. A railway vehicle truck according to claim 12 wherein an elastomeric bushing element is compressed between the inner and outer members.

14. A railway vehicle truck according to claim 13 wherein said bushing element consists of radially spaced inner and outer arcuate metal plates respectively spaced apart circumferentially from each other, and elastomeric blocks between said inner and outer plates and bonded to the same, said blocks being spaced apart circumferentially of said element.

15. A railway vehicle truck according to claim 14 wherein said inner and outer plates are in staggered relation with each other circumferentially of said element, the end portions of each outer plate overlapping the end portion of adjacent inner plates, said blocks being positioned respectively between the lapped end portions of inner and outer plates. 

1. A railway vehicle truck comprising a pair of axles spaced apart longitudinally of the truck, wheels mounted on the end portions of said axles, transversely spaced longitudinally extending side frames adapted to support current collection equipment intermediate their ends, said side frames having downwardly open jaws at their ends embracing the end portions of said axles, bearing devices mounted on said axles within said jaws, said jaws and said bearing devices having longitudinally spaced opposing respectively downwardly and upwardly facing transverse surfaces upwardly and inwardly inclined toward each other, said transverse surfaces being V-shaped in plan with their apices pointing longitudinally of the truck, a single pad of elastomeric material between each pair of opposing bearing device and jaw tranverse surfaces, said pads being sufficiently stiff to resist substantial vertical movement of said side frames and thereby prevent excessive variation in the height of current collection equipment carried thereby while being sufficiently resilient to provide adequate vertical cushioning for equipment supported from said side frames, and means connecting said side frames to each other for sufficient relative pivotal movement about a generally transverse axis to maintain, in cooperation with said pads, all said wheels in constant load-bearing engagement with the supporting track irrespective of varying vertical irregularities in the track rails.
 2. A railway vehicle truck according to claim 1 wherein said side frame connecting means comprises a substantially straight transverse transom member on each side frame extending toward and terminating in close proximity to the opposite side frame, said transom members being located symmetrically on opposite sides of the transverse axis of the truck, an inboard stub member on each side frame in transverse alignment with the transom member of the opposite side frame, and flexible connections between the transom members and corresponding stub members.
 3. A railway vehicle truck according to alcim 2 wherein said transom members have opposing surfaces transverse of the truck closely spaced apart longitudinally of the truck and formed with concentric arcuate recesses in their opposing transverse surfaces, there being a transverse bolster slidably suppOrted on said side frames and having a central depending pivot boss pivotally received between said arcuate recesses, upright springs carried by the ends of said bolster for supporting a vehicle body thereon, and means for connecting said bolster to a supported vehicle body for preventing swivel movements therebetween while permitting vertical and transverse deflection of said springs.
 4. A railway vehicle truck comprising a pair of axles spaced apart longitudinally of the truck, wheels mounted on the end portions of said axles, transversely spaced longitudinally extending side frames supported at their ends on the end portions of said axles, each said side frame being formed with a transverse transom member extending toward and terminating in close proximity to the opposite side frame, said transom members being located symmetrically on opposite sides of the transverse axis of the truck, an inboard stub member on each side frame in transverse alignment with the transom member of the opposite side frame, and flexible connections between the transom members and corresponding stub members.
 5. A railway vehicle truck according to claim 4 wherein said side frame stub members overlie the end portions of the corresponding transom members.
 6. A railway vehicle truck according to claim 5 wherein said pivotal connections comprise opposed respectively upwardly and downwardly facing horizontal surfaces on said transom members and said side frame stub members, a pad of elastomeric material interposed between said surfaces, and means tying said transom members and the corresponding stub members to each other vertically and thereby compressing said elastomeric pads.
 7. A railway vehicle truck according to claim 6 wherein said tying means comprises a vertical tension member passing through said opposed surfaces and said elastomeric pad, additional elastomeric pads surrounding said tension member on upwardly and downwardly facing surfaces respectively of said stub members and said transom members, and means on said tension member compressing said additional pads against the respective last-named surfaces.
 8. A railway vehicle truck according to claim 7 wherein depending and upstanding rims respectively encircle said downwardly and upwardly facing surfaces respectively of said stub members and said transom members, said elastomeric pads being of annular shape.
 9. A railway vehicle truck according to claim 5 wherein said pivotal connections comprise opposed downwardly and upwardly facing spherical surfaces on said stub members and transom members respectively, there being a pad of elastomeric material interposed between said surfaces, and means spaced transversely of the truck from the respective opposed spherical surfaces for tying the corresponding transom member and stub member to each other vertically and compressing said elastomeric pads.
 10. A railway vehicle truck according to claim 9 wherein each of said stub members is formed with a projection extending transversely from said downwardly facing surface away from the related side frame, and said tying means comprises a vertical tension member passing through said projection and the corresponding transom member.
 11. A railway vehicle truck according to claim 10 wherein additional elastomeric pad devices are seated on upper and lower surfaces of said projection and the corresponding transom stub surrounding said tension member, there being means on said tension member for compressing said additional pads against said last-named surfaces.
 12. A railway vehicle truck according to claim 4 wherein said transom members and said stub members are of tubular cross-section, one of said members having an end portion of reduced cross-section to permit mating insertion of the former into the latter.
 13. A railway vehicle truck according to claim 12 wherein an elastomeric bushing element is compressed between the inner and outer members.
 14. A railway vehicle truck according to claim 13 wherein said bushing eleMent consists of radially spaced inner and outer arcuate metal plates respectively spaced apart circumferentially from each other, and elastomeric blocks between said inner and outer plates and bonded to the same, said blocks being spaced apart circumferentially of said element.
 15. A railway vehicle according to claim 14 wherein said inner and outer plates are in staggered relation with each other circumferentially of said element, the end portions of each outer plate overlapping the end portion of adjacent inner plates, said blocks being positioned respectively between the lapped end portions of inner and outer plates. 